Measuring-transformer.



H. GEWEGKE & c. BAEUMLBR.

MEASURING TRANSFORMER.

APPLIOATION rum) NOV. 3, 1914.

1,133,466. Patented Mar. 30, 1915.

. UNITED sTATEs PATENT OFFICE.

HERMANN GEWECKEAND CHRISTIAN BAEUMLER, 0F NUREMBERG, GERMANY, AS-

SIGNOBS TO SIEMENS-SCHUCKERT WERKE, G. M. B. BL, 01 SIEMENSSTADT, NEAR BERLIN, GERMANY, A CORYORATION OF GERMANY.

MEASURING-TRANSFORMER.

Specification of Letters Patent.

Patented Mar. 30, 1915.

Application filed November 3, 1914. Serial No. 870,153.

To all whom it may concern Be it known that we, HERMANN Gnwnona and CHRISTIAN BAEUMLER, German subjects, residing at Nuremberg, Bavaria, Germany, have invented certain new and useful Improvements in Measuring-Transformers, of which the following is a specification.

Our present invention relates to a measuring transformer for electrical instruments and consists in brief in providing special arrangements for accurately attaining a desired ratio of transformation. Furthermore, a transformer constructed according to this invention will permit the ratio of transformation .to be adjusted either during manufacture or during testing.

Heretofore it had been usual to adjust the ratio of transformation in measuring transformers by switching on or oif one or more turns of the primary or secondary circuit. The adjustment obtained in this manner, however, is only relatively coarse, since always complete winding turns are thus switched on or olf.

For the exact adjustment of the ratio of transformation of the measuring transformer according to our present invention one or more turns of the secondary winding are arranged so as to be varied in position relatively to-the ma etic flux, so that either the entire cross-section of the magnetic flux or only a part thereof will be inclosedby said turn or turns. In this manner the auxiliary or additional turns of the. winding'which inclose the flux of the lines of force may be increased or decreased until the desired ratio of transformation is attained. Also if instead thereof the respective part of the magnetic fiux may be left unchanged and the number of the winding turns surrounding the same may be made greater or smaller or both of these methods may be combined.

In the drawings Figure 1 shows diagrammatically a simple form of a measuring transformer according to our invention, Fig. 2 is a cross-section through a modified form of transformer and Fig. 3 a top view taken on Fig. 2.

he body of the transformer shown in Fig. 1, which may for-instance be a current transformer, consists of sheets of iron a of ring-like shape into which a laminated core 6 is inserted which carries the coils of the transformer. The turns of the secondary winding which is shown in are designated by the letter 0 and the primary is shown by way of example at p. Wlth the end of these turns one or more additional turns 03 are connected which may be threaded through any one. of the holes 6, as shown, so that the convolution formed thereby will only partly surround the total magnetic flux. The E. M. F. which shall be generated in the turns d will now determine which of the holes must be used for receivmg the conductor (1 in order to obtain the effect of a certain desired number of additional turns. Also if only a single hole or slot e is provided the conductor 05 must be carried around a part of the magnetic flux in such a number of turns that the desired E. M. F. will be generated in the secondary winding.

The additional turns may be positioned at any desired point of the magnetic flux. In the construction shown in the drawing these turns are placed upon the central core of the part in Fig. 1

' transformer, it is, however, understood that may more easily be threaded through the holes of the iron core. The threading of a braided copper ribbon through the holes e of the iron body, however, is often not convenient and in. addition requires a proper connection with the main conductor of the winding. This inconvenience is avoided by a preferred modification of the transformer which is represented in Figs. 2 and 3.

The construction shown in Figs. 2 and 3 represents an adjustable auxiliary turn and comprises a rake which is inserted into properly spaced holes e leading through the iron body I). This rake consists of a plurality of conductive bars which are conductively connected with each other on the one side of the iron body carrying the magnetic flux, while on the other side these bars are provided with free ends serving for the connection of the adjusting conductor and eventually for aconductor leading to the secondary terminal of the apparatus of the transformer. Any one of these bars may be selected for connection with the wire of the auxiliary secondary winding to thus become and constitute a portion of the auxiliary winding. In the core I) of the transformer in Figs. 2 and 3 there are shown three holes 6 which divide the magnetic flux through the iron body into four parts. Ac-

cording to our invention the above-men tioned rake consists more particularly of five conducting bars 1, 2, 3, 4L and 5, of which three, namely the bars 2, 3 and 4, are inserted'in the holes 6 of the core, while two of said bars, namely 1 and 5 are passing said core on the outside thereof. On the one side of the core the end bar f is arranged for conductively connecting said bars 1, 2, 3, 4 and 5, while the other ends of said bars project freely on the other side of the iron core above the surface thereof. The adjusting conductor 03 as well as the conductor is leading to the terminal of the apparatus may now be fastened as desired to any one of the ends of the bars 1, 2, 3, 4L and 5.

In the drawing the adjusting conductor d, may for instance, be connected to the end of the bar 1 and the conductor leading to the terminal to the end of the bar 5. The adjusting conductor d together with the bar 1,

- the end bar f and the bar 5 will in this case form a full turn of the secondary winding. This turn will become ineffective as secondary turn, if the adjusting conductor (1 is also fastened to the bar 5. If therefore the adjusting conductor is fastened to one of the bars 2, 3 or 4: the effect will be obtained as if a turn were added to the winding. In order to switch ofi or render ineflective the secondary turn which is formed by the aid of said rake, the conductor is, could also be fastened to the bar 1 while the adjusting conductor (2 is connected withthis bar; for adding partial winding turns also the conductor [0 could be fastened to one of the bars 2, 3 and 4. If the points of connection for the conductors d and 72 are displaced, the greatest number of steps of adjustment will be obtainable with the smallest number of bars in the rake. If, for inand 712 may also be mounted upon a terminal board or the like and the connections made from the board instead of making the same at the ends of the bars of the rake.

Having thus described our inventionwe claim as new and desire to secure by Letters Patent of the United States 1. In a measuring transformer, the combination of a magnetizable core, a winding having an auxiliary portion, said auxiliary portion being adapted to encircle a smaller or greater part of the magnetic flux passing through said core.

2. In a measuring transformer, the com bination of a magnetizable core, a secondary winding comprising an additional or aux1l1- ary portion, said core having a number ofholes arranged therein for dividing the magnetic flux and permitting connection to be made by said additional portion throughanyone of said holes, whereby the ratio of transformation may be adjusted.

3. In a measuring transformer, the combination of a magnetizable core, a secondary winding, said core having a plurality of holes dividing the magnetic flux through said core, and an adjustable auxiliary turn in the form of a rake-shaped body of conductive material inserted into said holes to form a plurality of open turns, encirclingsaid flux to avarious extent and having their open ends projecting from said core thus permitting said secondary winding to include in circuit anyone of said turns for adjusting the ratio of transformation.

In testimony whereof we aflix our signae tures in presence of two witnesses.

HERMANN GEWECKE. CHRISTIAN BAEUMLER.

Witnesses for Hermann Gewecke:

VVOLDEMAR HAUPT, HENRY HASPER.

Witnesses for Christian Baeumler ALBERT BEsoLD, OSCAR BOCK. 

